Previous laser tuning schemes for space-based missions based on optical phase-locked loops (OPLLs) involved use of many RF electronics, complicated FPGA setups, and multiple distributed feedback lasers (DFBs) that are not fast-tunable.
NASA Goddard Space Flight Center developed a single, fast-tunable seed laser system that does not involve the use of any OPLLs. The system is based on dual sideband locking. Extra phase modulation is added onto a frequency locking system, generating artificial locking points with a known frequency offset, maintaining the stability of the selected frequency.
The system uses fewer components and simple programming requirements.